CONTENTS

  Title Page

  Copyright Page

  Preface

  1      Introduction
    1.1 Scope of the Standard
      1.1.1      Extent of the Standard
      1.1.2      Conformity of an Implementation With the Standard
    1.2 Structure of the Standard
    1.3 Design Goals and Sources
    1.4 Language Summary
    1.4a DEC Ada
    1.5 Method of Description and Syntax Notation
    1.6 Classification of Errors

  2      Lexical Elements
    2.1 Character Set
    2.2 Lexical Elements, Separators, and Delimiters
    2.3 Identifiers
    2.4 Numeric Literals
      2.4.1      Decimal Literals
      2.4.2      Based Literals
    2.5 Character Literals
    2.6 String Literals
    2.7 Comments
    2.8 Pragmas
    2.9 Reserved Words
    2.10 Allowable Replacements of Characters

  3      Declarations and Types
    3.1 Declarations
    3.2 Objects and Named Numbers
      3.2.1      Object Declarations
      3.2.2      Number Declarations
    3.3 Types and Subtypes
      3.3.1      Type Declarations
      3.3.2      Subtype Declarations
      3.3.3      Classification of Operations
    3.4 Derived Types
    3.5 Scalar Types
      3.5.1      Enumeration Types
      3.5.2      Character Types
      3.5.3      Boolean Types
      3.5.4      Integer Types
      3.5.5      Operations of Discrete Types
      3.5.6      Real Types
      3.5.7      Floating Point Types
      3.5.7a     Pragma Float_Representation
      3.5.7b     Pragma Long_Float (OpenVMS Systems Only)
      3.5.8      Operations of Floating Point Types
      3.5.9      Fixed Point Types
      3.5.10     Operations of Fixed Point Types
    3.6 Array Types
      3.6.1      Index Constraints and Discrete Ranges
      3.6.2      Operations of Array Types
      3.6.3      The Type String
    3.7 Record Types
      3.7.1      Discriminants
      3.7.2      Discriminant Constraints
      3.7.3      Variant Parts
      3.7.4      Operations of Record Types
    3.8 Access Types
      3.8.1      Incomplete Type Declarations
      3.8.2      Operations of Access Types
    3.9 Declarative Parts

  4      Names and Expressions
    4.1 Names
      4.1.1      Indexed Components
      4.1.2      Slices
      4.1.3      Selected Components
      4.1.4      Attributes
    4.2 Literals
    4.3 Aggregates
      4.3.1      Record Aggregates
      4.3.2      Array Aggregates
    4.4 Expressions
    4.5 Operators and Expression Evaluation
      4.5.1      Logical Operators and Short-circuit Control Forms
      4.5.2      Relational Operators and Membership Tests
      4.5.3      Binary Adding Operators
      4.5.4      Unary Adding Operators
      4.5.5      Multiplying Operators
      4.5.6      Highest Precedence Operators
      4.5.7      Accuracy of Operations with Real Operands
    4.6 Type Conversions
    4.7 Qualified Expressions
    4.8 Allocators
    4.9 Static Expressions and Static Subtypes
    4.10 Universal Expressions

  5      Statements
    5.1 Simple and Compound Statements-Sequences of Statements
    5.2 Assignment Statement
      5.2.1      Array Assignments
    5.3 If Statements
    5.4 Case Statements
    5.5 Loop Statements
    5.6 Block Statements
    5.7 Exit Statements
    5.8 Return Statements
    5.9 Goto Statements

  6      Subprograms
    6.1 Subprogram Declarations
    6.2 Formal Parameter Modes
    6.3 Subprogram Bodies
      6.3.1      Conformance Rules
      6.3.2      Inline Expansion of Subprograms
    6.4 Subprogram Calls
      6.4.1      Parameter Associations
      6.4.2      Default Parameters
    6.5 Function Subprograms
    6.6 Parameter and Result Type Profile-Overloading of Subprograms
    6.7 Overloading of Operators

  7      Packages
    7.1 Package Structure
    7.2 Package Specifications and Declarations
    7.3 Package Bodies
    7.4 Private Type and Deferred Constant Declarations
      7.4.1      Private Types
      7.4.2      Operations of a Private Type
      7.4.3      Deferred Constants
      7.4.4      Limited Types
    7.5 Example of a Table Management Package
    7.6 Example of a Text Handling Package

  8      Visibility Rules
    8.1 Declarative Region
    8.2 Scope of Declarations
    8.3 Visibility
    8.4 Use Clauses
    8.5 Renaming Declarations
    8.6 The Package Standard
    8.7 The Context of Overload Resolution

  9      Tasks
    9.1 Task Specifications and Task Bodies
    9.2 Task Types and Task Objects
    9.3 Task Execution-Task Activation
    9.4 Task Dependence-Termination of Tasks
    9.5 Entries, Entry Calls, and Accept Statements
    9.6 Delay Statements, Duration, and Time
    9.7 Select Statements
      9.7.1      Selective Waits
      9.7.2      Conditional Entry Calls
      9.7.3      Timed Entry Calls
    9.8 Priorities
    9.8a Pragma Time_Slice (OpenVMS and Digital UNIX Systems Only)
    9.8b Pragma Passive (OpenVMS Alpha and Digital UNIX Only)
    9.9 Task and Entry Attributes
    9.10 Abort Statements
    9.11 Shared Variables
    9.12 Example of Tasking
    9.12a Task Entries and OpenVMS Asynchronous System Traps (OpenVMS Systems Only)

  10     Program Structure and Compilation Issues
    10.1 Compilation Units-Library Units
      10.1.1     Context Clauses-With Clauses
      10.1.2     Examples of Compilation Units
    10.2 Subunits of Compilation Units
      10.2.1     Examples of Subunits
    10.3 Order of Compilation
    10.4 The Program Library
    10.5 Elaboration of Library Units
    10.6 Program Optimization

  11     Exceptions
    11.1 Exception Declarations
    11.2 Exception Handlers
    11.3 Raise Statements
    11.4 Exception Handling
      11.4.1     Exceptions Raised During the Execution of Statements
      11.4.2     Exceptions Raised During the Elaboration of Declarations
    11.5 Exceptions Raised During Task Communication
    11.6 Exceptions and Optimization
    11.7 Suppressing Checks

  12     Generic Units
    12.1 Generic Declarations
      12.1.1     Generic Formal Objects
      12.1.2     Generic Formal Types
      12.1.3     Generic Formal Subprograms
    12.1a Pragma INLINE_GENERIC
    12.1b Pragma SHARE_GENERIC
    12.2 Generic Bodies
    12.3 Generic Instantiation
      12.3.1     Matching Rules for Formal Objects
      12.3.2     Matching Rules for Formal Private Types
      12.3.3     Matching Rules for Formal Scalar Types
      12.3.4     Matching Rules for Formal Array Types
      12.3.5     Matching Rules for Formal Access Types
      12.3.6     Matching Rules for Formal Subprograms
    12.4 Example of a Generic Package

  13     Representation Clauses and Implementation-Dependent Features
    13.1 Representation Clauses
    13.1a The Pragma Component_Alignment
    13.2 Length Clauses
    13.2a The Pragma Task_Storage
    13.2b The Pragma Main_Storage (OpenVMS VAX Systems Only)
    13.3 Enumeration Representation Clauses
    13.4 Record Representation Clauses
    13.5 Address Clauses
      13.5.1     Interrupts
    13.6 Change of Representation
    13.7 The Package System
      13.7.1     System-Dependent Named Numbers
      13.7.2     Representation Attributes
      13.7.3     Representation Attributes of Real Types
    13.7a General DEC Ada Additions to the Package System
      13.7a.1    Address Type Declarations
      13.7a.2    Enumeration Type for Identifying Type Classes
      13.7a.3    Non-Ada Exception
      13.7a.4    Hardware-Oriented Types and Functions
      13.7a.5    Convenient Unsigned Longword Declarations
      13.7a.6    Global Symbol Values
    13.7b System-Specific DEC Ada Additions to the Package System
      13.7b.1    VAX Floating Point Types (OpenVMS Systems Only)
      13.7b.2    IEEE Floating Point Types (OpenVMS Alpha and Digital UNIX Systems Only)
      13.7b.3    OpenVMS Asynchronous-System-Trap-Related Declarations (OpenVMS Systems Only)
      13.7b.4    VAX Processor and Device Register Operations (OpenVMS VAX Systems Only)
      13.7b.5    Interlocked-Instruction Procedures (OpenVMS and Digital UNIX Systems Only)
      13.7b.6    Atomic Procedures (Alpha Systems Only)
      13.7b.7    Interlocked-Queue-Instruction Procedures (OpenVMS Systems Only)
    13.8 Machine Code Insertions
    13.9 Interface to Other Languages
    13.9a DEC Ada Import and Export Pragmas
      13.9a.1    Importing and Exporting Subprograms
        13.9a.1.1    Importing Subprograms
        13.9a.1.2    Attribute for Optional Parameters
        13.9a.1.3    Exporting Subprograms
        13.9a.1.4    Controlling the Passing Mechanisms for Parameters and Function Results
      13.9a.2    Importing and Exporting Objects
        13.9a.2.1    Importing Objects
        13.9a.2.2    Exporting Objects
        13.9a.2.3    Importing and Exporting Objects with the Pragma Common_Object
      13.9a.3    Importing and Exporting Exceptions (OpenVMS Systems Only)
        13.9a.3.1    Importing Exceptions (OpenVMS Systems Only)
        13.9a.3.2    Exporting Exceptions (OpenVMS Systems Only)
    13.9b The Pragma Interface_Name
    13.10 Unchecked Programming
      13.10.1    Unchecked Storage Deallocation
      13.10.2    Unchecked Type Conversions

  14     Input-Output
    14.1 External Files and File Objects
    14.1a File Elements
    14.1b Specification of the FORM Parameter in DEC Ada
      14.1b.1    The FORM Parameter on OpenVMS Systems
      14.1b.2    The FORM Parameter on Digital UNIX Systems
    14.2 Sequential and Direct Files
      14.2.1     File Management
      14.2.2     Sequential Input-Output
      14.2.3     Specification of the Package Sequential_IO
      14.2.4     Direct Input-Output
      14.2.5     Specification of the Package Direct_IO
    14.2a Relative and Indexed Files (OpenVMS Systems Only)
      14.2a.1    File Management (OpenVMS Systems Only)
      14.2a.2    Relative Input-Output (OpenVMS Systems Only)
      14.2a.3    Specification of the Package Relative_IO (OpenVMS Systems Only)
      14.2a.4    Indexed Input-Output (OpenVMS Systems Only)
      14.2a.5    Specification of the Package Indexed_IO (OpenVMS Systems Only)
    14.2b Mixed-Type Input-Output
      14.2b.1    File Management
      14.2b.2    Item Input-Output
      14.2b.3    Sequential Mixed Input-Output
      14.2b.4    Specification of the Package Sequential_Mixed_IO
      14.2b.5    Direct Mixed Input-Output
      14.2b.6    Specification of the Package Direct_Mixed_IO
      14.2b.7    Relative Mixed Input-Output (OpenVMS Systems Only)
      14.2b.8    Specification of the Package Relative_Mixed_IO (OpenVMS Systems Only)
      14.2b.9    Indexed Mixed Input-Output (OpenVMS Systems Only)
      14.2b.10  Specification of the Package Indexed_Mixed_IO (OpenVMS Systems Only)
    14.3 Text Input-Output
      14.3.1     File Management
      14.3.2     Default Input and Output Files
      14.3.3     Specification of Line and Page Lengths
      14.3.4     Operations on Columns, Lines, and Pages
      14.3.5     Get and Put Procedures
      14.3.6     Input-Output of Characters and Strings
      14.3.7     Input-Output for Integer Types
      14.3.8     Input-Output for Real Types
      14.3.9     Input-Output for Enumeration Types
      14.3.10    Specification of the Package Text_IO
    14.4 Exceptions in Input-Output
    14.5 Specification of the Package IO_Exceptions
    14.5a Specification of the Package Aux_IO_Exceptions (OpenVMS Systems Only)
    14.6 Low Level Input-Output
    14.7 Example of Input-Output
    14.7a Example of Additional DEC Ada Input-Output

  Predefined Language Attributes

  Predefined Language Pragmas

  Predefined Language Environment

  D Glossary

  E Syntax Summary

  F Implementation-Dependent Characteristics
    F.1 Implementation-Dependent Pragmas
    F.2 Implementation-Dependent Attributes
    F.3 Specification of the Package System
    F.4 Restrictions on Representation Clauses
    F.5 Restrictions on Unchecked Type Conversions
    F.6 Conventions for Implementation-Generated Names Denoting Implementation-Dependent Components in Record Representation Cla
    F.7 Interpretation of Expressions Appearing in Address Clauses
    F.8 Implementation-Dependent Characteristics of Input-Output Packages
      F.8.1      DEC Ada Input-Output Packages on OpenVMS Systems
        F.8.1.1      Interpretation of the FORM Parameter on OpenVMS Systems
        F.8.1.2      Input-Output Exceptions on OpenVMS Systems
      F.8.2      Input-Output Packages on Digital UNIX Systems
        F.8.2.1      Interpretation of the FORM Parameter on Digital UNIX Systems
        F.8.2.2      Input-Output Exceptions on Digital UNIX Systems
    F.9 Other Implementation Characteristics
      F.9.1      Definition of a Main Program
      F.9.2      Values of Integer Attributes
      F.9.3      Values of Floating Point Attributes
        F.9.3.1      F_floating Characteristics
        F.9.3.2      D_floating Characteristics
        F.9.3.3      G_floating Characteristics
        F.9.3.4      H_floating Characteristics
        F.9.3.5      IEEE Single Float Characteristics
        F.9.3.6      IEEE Double Float Characteristics
      F.9.4      Attributes of Type DURATION
      F.9.5      Implementation Limits

  G Ada Language Interpretations

  Postscript :  Submission of Comments